login.php in Zenas PaoBacheca Guestbook 2.1, when register_globals is enabled, allows remote attackers to bypass authentication and gain administrative access by setting the login_ok parameter to 1.
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
5.0% chance of exploitation in the next 30 days; higher than 92% of CVEs (scores of 2026-10-31)